The issue with being a beginner is not knowing what sound you like. While the ie200 are great you might not like the sound signature, so it’s best to get a couple cheap iem’s $20-50 that are different. Get something warm, something bright and something neutral etc. Then once you figure out what you like then you can invest more money into the hobby.

I don’t know much about iem’s but I do have really expensive headphones. I started with 5-6 headphones at about $100, then picked by favorite 3-4 and bought the upgraded versions at $500-600. Once I figured out what sound I liked I went to an audio store and jumped into $2000 headphones and I haven’t looked back.

My audio journey took 8 years so there’s no rush to spend money.

If I could keep anything it would be the Ether 2 and the Andromeda but if it was the cheapest headphone that I’d be happy with, it would be the DT880 600ohm and the Truthear hexa or the FAAEAL Iris 2.0

While your HE6se gets loud enough, it might sound compressed if it’s under powered. I found that my HE6se V2 had a tighter bass and better stage depth when given a lot of power. I remember seeing an interview with a Hifiman employee that said the v2 needs 10W per channel.

To see if you need more power you could just buy a cheap $100 speaker amp like a Fosi Audio v3 or a S.M.S.L DA-6, and pair it with Hifiman’s HE-Adapter, or get Another cable . If it doesn’t sound better then just return the amp.

I watched an interview with a Sennheiser audio engineer and he laughed at the idea of break in. He said it would be ridiculous for Sennheiser to sell headphones that will sound different in 50-100 hours.

Later on in the interview they spoke with Dan Clark and he has a wall where he burns in drivers before he matches them.

So it seems like burn in is real but it’s done by the manufacturer, maybe cheaper gear doesn’t get burned in. I still burn in all of my gear just in case though.